Human fossil fuel emissions are advancing towards a critical climate threshold at a rate twice as fast as previously anticipated, according to a new report. The 1.5C limit, a key component of the Paris climate agreement, could be breached as early as 2029, rather than the mid-2030s. Record carbon dioxide emissions over the past three years and an improved understanding of the impact of fossil fuel burning on the atmosphere are cited as key factors.
Global temperatures for 2023 are predicted to approach 1.5C above pre-industrial levels, marking a significant increase since the world began using coal, oil, and gas heavily around 1850. Scientists fear that the world will soon emit enough greenhouse gases to maintain these elevated temperatures for an extended period. The 1.5C limit is particularly crucial for developing countries and small island nations, who are at risk of losing their homes to rising sea levels if this level of warming is surpassed.
To determine when the world will reach the 1.5C limit, scientists established a “budget” for the amount of carbon that can still be emitted before this threshold is crossed. The current annual level of emissions is around 40 billion tonnes. The Intergovernmental Panel on Climate Change (IPCC) projected that this threshold would be crossed permanently by the middle of the next decade. However, new analysis suggests that this could happen much sooner.
Researchers considered that the IPCC’s data only extended up to 2020 and adjusted the budget downwards to account for carbon used over the last three years. They also reassessed the role of other non-carbon factors that impact warming, such as aerosols, which cool the atmosphere by reflecting sunlight back into space. As efforts to reduce air pollution and the use of heavily polluting fossil fuels decrease the number of aerosols in the atmosphere, temperatures are expected to rise faster than previously anticipated.
This new understanding of aerosols’ role reduces the remaining 1.5C budget by 100 billion tonnes. Combined with the extra carbon and other small adjustments, the total remaining budget is now estimated at 250 billion tonnes. To avoid exceeding the 1.5C limit, global carbon dioxide emissions would need to reach net zero by 2034, significantly earlier than the current expectation of 2050.
Key Takeaways:
- Human fossil fuel emissions are accelerating the approach to a critical climate threshold, potentially leading to a constant breach of the 1.5C limit by 2029, instead of the previously predicted mid 2030s.
- The reduction of aerosols in the atmosphere due to efforts to reduce air pollution and fossil fuel usage could cause temperatures to rise faster than previously anticipated, as aerosols help cool the atmosphere by reflecting sunlight back into space.
- To prevent surpassing the 1.5C warming threshold, global carbon dioxide emissions would need to reach net zero by 2034, significantly earlier than the current target of 2050.
“Human fossil fuel emissions are threatening a key climate threshold twice as quickly as previously thought, a new report says. Researchers say the 1.5C limit could be continually breached by 2029, rather than the mid 2030s. They say record emissions of carbon dioxide over the past three years are a key factor.”
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